1. Field of the Invention
The present invention relates to aqueous gels having topical pharmaceutical activity, and methods of treating topical conditions by using said gels.
2. Description of the Prior Art
Pharmaceutical agents effective in topical application, e.g., for treating dermatological conditions, generally must be incorporated into a suitable ointment, gel, lotion or cream vehicle to promote uniform application and effective transdermal absorption.
It is often desirable in treating certain topical conditions with agents such as antifungals, antihistamines or anti-inflammatory drugs to concomitantly apply a bactericidal and/or bacteriostatic (antiseptic) agent to the skin to prevent bacterial infection or re-infection of the affected area. Rather than applying the primary topical agent and the bactericidal or antiseptic agent separately, it has been proposed to administer the primary agent (e.g., antifungal or anti-inflammatory) in a vehicle or matrix which itself possesses a high degree of bactericidal or bacteriostatic activity.
Ethyl alcohol, also known as ethanol or more simply "alcohol", is known to be highly bactericidal in high concentration. Topical liquid preparations comprising a dermatologically active agent dissolved or suspended ethyl alcohol, which preparations display both bactericidal activity and the activity of the dissolved or suspended agent, are known in the prior art. Such liquid alcohol-containing preparations suffer from a number of drawbacks, however. While ethyl alcohol is bactericidal in high concentrations, it exhibits poor bacteriostatic or antiseptic activity and infection or re-infection of the treated area not long after application of liquid alcohol-containing preparations is common. Furthermore, while alcohol in liquid form enhances the penetrability of the dissolved pharmaceutical agent for a brief period of time, the alcohol applied to exposed areas quickly evaporates and does not exhibit a long-term absorption-enhancing effect. Liquid alcohol-containing preparations are also inconvenient to store, carry and apply, and much spillage and waste is entailed in the application of such preparations.
Alcohol-containing gels and gel-like vehicles for pharmaceutical agents are known in the prior art. By way of example, U.S. Pat. No. 4,540,572 discloses a gel-like ointment containing indomethacin as well as alcohol to be applied topically, but intended to achieve systemically significant blood levels of the indomethacin for treatment of inflammatory and degenerative rheumatic diseases, not for topical therapy. There is no disclosure in that patent, however, of any bactericidal or antiseptic activity for the vehicles taught, and indeed, the concentration of alcohol in the vehicles (30-50%) is insufficient to exhibit significant antimicrobial activity.
U.S. Pat. No. 4,593,048 teaches compositions including high concentration of lower alcohols and systemically active pharmaceutical agents, whereby the compositions are applied topically (including in gel form) but the active ingredient is intended to be absorbed percutaneously into the bloodstream. No disclosure of the use of such composition for treatment of topical inflammations, dermatoses, etc. is included in that patent; nor is there any teaching of gels containing high alcohol concentrations with topically active ingredients as well as significant concentrations of water. The lack of water in the gel compositions containing substantial alcohol concentrations significantly decreases their antiseptic potency. Addition of water to the gels disclosed in U.S. Pat. No. 4,593,048 which already contain high alcohol concentration would destroy their gel-like consistency.
Hence, the prior art does not teach topical compositions containing high concentrations of alcohol in a form which maximizes its bactericidal and antiseptic properties and enables it to act as a long term penetration enhancer for a topically active pharmaceutical agent.